This invention relates to a system for switching high power pulses into a load, such as a pulsed linear particle accelerator, using a saturable transformer, and further relates to a structure for the saturable transformer.
Many pulse power applications, such as a pulsed linear accelerator or a copper vapor laser for isotope separation, require both reliability and high repetition rates. Usually a pulse forming network, or just a capacitor, is charged to a selected voltage, and maintained charged until a power pulse is to be delivered to a load. An electric switch in series with the load is used to connect the storage network to the load. Electric switches that under certain conditions have been used reliably include triggered spark gaps, ignitrons and thyratrons. These switches isolate very well in the open state so the storage network can be fully charged without leakage, and held charged a long time before activation of the switch. A saturable transformer can also be used as a switch with low leakage current in such a switching system. Such a saturable transformer may be provided with a step-up turn ratio to produce a high output voltage. The resultant magnetic switching can provide the high repetition rates usually required, and the system becomes both economical and reliable because it utilizes just a saturable transformer. It does not require a control terminal (grid or other control electrode) as in other electric switches.
As just noted above, a high step-up turn ratio is often desired in the power pulse switching transformer. However, the inductance of the secondary winding is proportional to the square of the number of turns in the secondary winding and must be kept as small as possible; consequently the number of primary turns must be made as small as possible. This suggests a switching transformer having fractional turns in the primary winding in order to produce a high step-up ratio with a small output inductance. For instance, if the transformer is made with a small number n of turns in the secondary winding, such as 8, and a fractional turn 1/n in the primary winding, the output voltage is stepped up by the ratio n:1/n which is equal to n.sup.2. A fractional turn is a turn that links only part of the total flux, i.e., links only a fraction of the core linked by turns of the other winding.